In "50/50," the mildly comedic cancer drama starring Joseph Gordon-Levitt as the stricken Adam, the only thing people do worse than break the news of his diagnosis is receive it. When Adam learns that the source of his persistent back pain is a malignant tumor on his spine, so exotically named that an entire Scrabble game couldn't spell it, he's mostly deciphering his doctor's jargon-laden spoken notes. He swoons; the doctor goes all hazy; and he wanders over to the window as Radiohead's "High and Dry" begins playing. When he breaks the news to his mother (Anjelica Huston) over dinner two days later, she bursts into tears and rushes to make him green tea, because she heard it reduces the chance of cancer. His flaky struggling-artist girlfriend Rachael (Bryce Dallas Howard) lamely promises she'll stick through it, then as a show of support adopts a greyhound named Skeletor. When his co-workers at the Seattle public radio station where he works throw him a party, he's beset by a line of well-meaning folks who have no idea what to say, amplifying awkwardness to the point of a near-assault.

The only person who seems to jump in with both feet is Adam's best friend Kyle, played by Seth Rogen. Rogen's friend Will Reiser wrote the screenplay after going through just this scenario — dude in his 20s diagnosed with the emperor of maladies; Rogen is in essence playing a younger, coarser version of himself. When Kyle hears the news, he gamely babbles about how likely Adam is to survive, how he's young and strong, how the 50/50 odds that Adam has gleaned from some website dedicated to his cancer actually sound like a winning hand. In the moment the chipper front feels right, but Kyle's attempted nonchalance, and Adam's, and that of most young men, probably, who would find themselves staring down death just as adulthood is really beginning, wears out when chemo drains the life out of the patient, when it becomes clear that no one but the dying can really relate, and when the prospect of something worse than a painful survival looms. The risk of talking about death by not talking about death is that, in the end, you may really not be talking about death.

Director Jonathan Levine, in just his third feature film, holds the story firmly on Adam, who appears in nearly every scene. We feel the weight of his descent. Other than the pot-laced macaroons and the possibility of sympathy sex, cancer co-stars as an irredeemable bummer. Almost painfully mild-mannered at the time of his diagnosis, Adam becomes grouchier and more irascible as his life frays and mortality looms. His therapist, the too-young-for-there-not-to-be-sparks Katherine (Anna Kendrick, of "Up in the Air" fame), can't break the fall of his ever-darker moods; even she doesn't want to, or really know how to, change the conversation from a clinical handling of how people feel with the big C to how this individual, this young man, should face the big D. And as Adam begins to admit to himself, finally, that he's not just dealing with a hard snag but possibly, very possibly, an early death, he snaps to.

"50/50" is a very good movie, if shy of great, and in it there is a moment in which the empathy the film has built for an hour and a half all clamors to the fore in a sudden emotional rush, and for a second, your heart will break into pieces. Surrounded by technology and doctors and family, all there to see him through, Adam is the loneliest person in the world. There's a hard conversation to undertake before that moment arrives, and "50/50" ably shows how not to have it.